Chemical Properties
Chemically, the
metals differ from the nonmetals in that they form positive ions
and basic oxides and hydroxides. Upon exposure to moist air, a
great many undergo corrosion, i.e., enter into a chemical
reaction; e.g., iron rusts when exposed to moist air, the oxygen
of the atmosphere uniting with the metal to form the oxide of
the metal. Aluminum and zinc do not appear to be affected, but
in fact a thin coating of the oxide is formed almost at once,
stopping further action and appearing unnoticeable because of
its close resemblance to the metal. Tin, lead, and copper react
slowly under ordinary conditions. Silver is affected by
compounds such as sulfur dioxide and becomes tarnished when
exposed to air containing them. The metals are combined with
nonmetals in their salts, as in carbides, carbonates, chlorides,
nitrates, phosphates, silicates, sulfides, and sulfates.
The
Electromotive Series
On the basis of their ability to
be oxidized, i.e., lose electrons, metals can be arranged in a list
called the
electromotive
series
,
or replacement series. Metals toward the beginning of the
series, like cesium and lithium, are more readily oxidized than
those toward the end, like silver and gold. In general, a metal
will replace any other metal, or hydrogen, in a compound that it
precedes in the series, and under ordinary circumstances it will
be replaced by any metal, or hydrogen, that it
follows.
